Tractor-trailer steering apparatus



June 19, 1951 G. E. ARMINGTON 2,557,066

TRACTOR-TRAILER STEERING APPARATUS Filed May 15. 1946 7 sheets-sheet 1 u INVE N 70d G50/PGE E AKM/Nam,

June 19, 1951 G. E. ARMINGTON TRACTOR-TRAILER STEERING APPARATUS Filed May 15, 194e '7 Sheets-Sheet 2 N m mw wm W4 TTO/TNEYS June 19, 1951 G. E. ARMINGTON 2,557,066

TRACTOR-TRAILER STEERING APPARATUS Fncd nay 1s, `194e 7 sheets-sheet s June 19, 1951 G. E. ARMINGTON 2,557,066

TRACTOR-TRAILER STEERING APPARATUS Filed May 15. 1946 7 Sheets-Sheer. 4

June 19, 1951 G. E. ARMINGTON 2,557,066

TRAcToR-TRAILER STEERING APPARATUS Filed May l5, 1946 7 Sheets-Sheet 5 VvE/WOR GEORGE E. /l/vm/voro/v June 1911951 G. E. ARMING-roN 2.557.066

TRACTOR-TRAILER STEERING APPARATUS Filed May 15,v 194e '7 sheets-sheet e VENT 73 ylg, @wmv ITORNEYJ June 19, 1951 G. E. ARMINGTON 2,557,066

TRACTOR-TRAILER STEERING APPARATUS Filed May 15, 1946 7 Sheets-Sheet 7 @IQ/awww.

i /fvvf/v rm GEORGE E. ARNm/670m TORNEYJ jPaenfeJjJeee le;V 1951."v f

TRACTOR-TRAILER. STEERING APPARATUS George E. Armington, south Eolid, ohio, ae-

signor to The Euclid Road Machinery Co.,

Euclid, Ohio, a corporation of Ohio Application Mey 15, 1946, serial No. 669,906

(el. 18o-79.2)

16 Claims.

This invention relates to earth moving apparatus, and more particularly to that type of apparatus includinga trailing load carrying body and a motor tractor for hauling it, the two being pivotally connected on a vertical axis by the connecting hitch. The invention has steering mechanism.`

The apparatus here involved contemplates a trailer body of relatively large size. with a capacity of ve to twenty-live yards and hence of considerable weight when fully loaded.

The present application illustrates and describes two servomotors, primary and booster, operating at an angle to each other and cooperating in special manner to provide a steering operation between a tractor and a trailer. These servomotors are supplied with I'luid pressure by means of two pumps, which may be of different capacity by means of which the steering operation may be slow when a slight tum is desirable or may be fast when a sudden or sharp turn is desirable. All claims of this application include or involve the booster servomotor or its equivalent. Claims to the two-speed operation of my device are incorporated in my copending application, Serial No. 669,907, led of even date herewith.

One object of the invention is to provide improved steering mechanism in which the steering effect is accomplished, not by turning the wheels or crawlers relative to the body or chassis of either the trailer or tractor, or by diierential drive of two opposite wheels, but by compelling relative turning motion of the tractor and trailer, bodily with reference to each other, about the hitch axis, and preferably by turning motion of the tractor rather than of the trailer.

A further object is to so arrange the tractor and trailer as to provide not only fairly uniform distribution of total weight as between the spporting wheels, and to insure suiiicient traction from the driving wheels, but also to enable the heavy mass andweight'of the trailer to be used, in anchor or fulcrum fashion, as a more or less stable base with reference to which swinging or steering motion of the tractor is produced.

Another object is to provide improved steering mechanism of the character described including motor or jack means, mounted upon the trailer and effective upon the tractor for turning the same to produce a steering effect, together withall necessary control devices therefor.

Still another object is to provide improved to do with the y steering mechanism of the character described,

in which the steering effect is produced by two uid pressure servomotors operating horizontally at or near a right angle to each other, the i'lrst or primary` motor serving and eiective throughout its range of operation, and the second or booster motor supplementing the first as f the steering operation of the ilrst becomes less efcient.

Still another object is to provide steering mechanism for producing relative motion between tractor and trailer, in the manner described, including a servomotor operating across dead center, together with automatic control means sensitive to the angular relation between tractor and trailer and arranged to always insure effective operation of the servomotor on either side of the dead center across which it operates.

Another object is to provide improved steering mechanism, including two servomotors effective to produce relative swing between tractor and trailer, as described, one thereof operating vacross dead center, together with automatic means for reversing the direction of operating motion of the other motor, to steer in either direction.

Another object is'to provide improved steering mechanism operated by two servomotors operating upon cranks one at an angle to its crank and the other at dead center with its crank when the parts are in neutral position, together with control means for insuring harmonious cooperation, between said servomotors at various positions no matter how they are related to the cranks.

Further objects of the invention in part are obvious and in part will appear more in detail hereinafter.

In the drawings, which represent one suitable embodiment of the invention, Fig. 1 is a side elevation of the complete apparatus;

Fig. 2 is a detail sectional elevation on the line 2 2, Fig. 7, illustrating a part of the operating connections for the automatic valve;

Fig. 3 is a detail plan view fromthe position oi' line 3-3, Fig. 1, illustrating certain yielding connections in the operating mechanism for the 1 1, Fig. l, illustrating the steering servomotorsr and the controlling devices therefor;

Fig. 8 is a portion of Fig. 1 enlarged and with 9 portons in section to more clearly show the construction;

Fig. 9 is a fragmental sectional View taken along the line 9-9 o Fig. 8;

Fig. l is a fragmental sectional view taken along the line IIl-i il of Fig. 8;

Fig. il is a diagrammatic view, substantially a conventionalized section on the line II-II, Fig. 5, illustrating the steering valves and the automatic control Valve, and a part of the operating connections therefor, the parts being shown in neutral position;

Fig. 12 is a similar view, with the operating connections omitted, valve Il being shown in its operating position assumed when the steering eiect has been to the left (crank at Ila) and the valves 48 and 49 are in their positions assumed when the operator has adjusted them for slow speed steering to the right;

Fig. 13 is a similar view, with valve 50 in the same position and valves 48s and 49 adjusted for high speed steering to the right;

Fig. 14 is a similar view, illustrating valve 5D in its neutral position and valves 48 and 49 in their right-hand high speed steering positions;

Fig. 15 is a similar view, illustrating valve 50 in its operating position assumed when the steering eect has been to the right (crank at I01b) and with valves 48 and 49 adjusted to their left-hand low speed steering positions;

Fig. 16 is a view taken along the line lli- I6 of Fig. '7, with the drivers seat and steering mechanism omitted to more clearly show the hitch; While Fig. 17 is an enlarged sectional View of the pump taken along the line I1-I1 of Fig. 6.

While apparatus embodying the invention may take a Variety of forms, for purposes of illustration, and in no sense of limitation, the invention has been illustrated in the form of earth moving apparatus including a tractor Ill and a trailer II, both of more or less rigid form, pivotally connected to turn relatively to each other about a vertical axis indicated by the line marked I2 in Fig. 1 and indicated as a point in Fig. 7, this axis of course being at the hitch.

The tractor may be of any suitable form but is shown as including a frame or chassis I3 mounted upon wheels I4 and supporting in advance of said wheels the usual driving or operating motor I5, which overhangs or projects forward beyond the tractor axle and thus assists in balancing the load of the trailer and producing good tractive eiect of the driving or hauling Wheels I4 upon the road. As shown in Fig. 6 the tractor may also support -a pump unit, marked I6, and a tank or reservoir I1 forming part of the hydraulic operating mechanism, as will appear more fully hereafter, such arrangement enabling the pump unit readily to be operatively connected to motor I5 as will be readily understood.

The trailer II includes a chassis or frame marked generally I8 supported upon wheels I9 and carrying a scoop form body 20 which, in this case, is usually of relatively large capacity, holding up t0 twenty or more yards of earth, representing a heavy load of many tons. The body is supported between the wheels I9 and a forwardly projecting drawbar portion 2| of the chassis, the forward end of which is provided with projecting brackets or arms 22 pivotally connected at the hitch axis I2, as by pins 23, to arms or brackets 24 on a tubular post or pillar 25 iixedly mounted on the chassis of the tractor,

d as shown in Figs. 1 and 16. At its upper end this post is provided with an operating crank arm 21. The details of the'4 hitch connection form no part of the present invention but are described in detail in my copending application Serial No. 666,650, filed May 2, 1946, now Patent No. 2,460,725 granted February 1, 1949, to which reference may be had for further description. It is suieient to state here that turning of post 25 about axis I2 causes chassis I3 to turn with it.

Both the wheels I4 on the tractor and I9 on the trailer are of the nonsteering variety, having no turning steering movement with respect to either the tractor or the trailer, steering being accomplished entirely, in this instance, by relative movement, bodily, of the tractor and trailer with reference to each other about the vertical axis I2 at the hitch.

The mounting ofthe scoop body 29 in ad- Vance of Wheels i9 and heavier toward the front end of the trailer, when the body is loaded, provides a relatively heavy trailer mass or weight which acts more or less as a stable fulcrum or anchor, with reference to which the tractor is turned during the steering operation. In other words, the'steering effect may be said to consist more of tractor than of trailer motion, so much so that in actual operation when a steering effect is produced, it almost seems as though the tractor wheels slide or skid sidewise about the trailer as a base, but of course, that effect is not so marked as to reduce tractive friction below that required for efficient haulage.

Relative steering swing between tractor and trailer may be produced in any suitable manner, but in the arrangement shown is secured from a power driven device by operating connections effective upon the crank arm 21. As illustrated more particularly in Fig. 7, crank arm 21 is provided with a crank pin 28 to which are connected yokes 29 on the piston rods 30, 3I of pistons 32,33 of primary and booster double acting servomotors or jacks, 34, 35, respectively, both of double acting hydraulic form and mounted at their rear ends to turn upon pivots 36 on the frame I8. Some of the advantages of my invention might be realized using a single steering motor, but special advantages will be apparent in the use of two motors as shown.

Piston 32 of the first or primary motor is actuated bythe supply of fluid, such as oil under pressure, to and from its chambers 34a, 34h, and piston 33 is actuated by supply to and from its chambers 35a, 35h.

The hydraulic system includes a tank or reservoir I1, large and small pumps 38, 39 forming part of the pump unit I6, controlling valve devices for the servomotors 34, 35, housed as a unit in a casing 40, Fig. 5, a pressure limit or relief valve 4I, a check valve 42 and a swivel joint 43, all interconnected by pipes or conduits later to be referred to.

The same hydraulic system may include valve devices in a Valve unit 44 communicating by conduits with servomotors 45, 45, 41, which may be employed for various purposes in operation of the scoop body, such as for raising and lowering the same, for operating the front apron or ejector gate thereof, or for like purposes, and which form no part of the present invention and therefore require no detailed description.

While the control mechanism used for steering purposes may be mounted either on the tractor or trailer, in the present system substantially all the parts thereof are mounted upon the trailattacca er, thus simplifying the mechanism, because the only connections in the hydraulic system which cross the swing joint between tractor and trailer are conduits, portions of which may be madev of flexible tubing where theaxis of swing is crossed, but in the present instance they pass through the vswivel joint 43, located on the axis I2.

In the present steering mechanism, operated as itis by fluid pressure, the controlling devices are actuated by the operator by means of a steering wheel, lever or other device of usual form. and include valve devices which may be actuated to produce a steering effect, to wit, relative steering swing between tractor and trailer. In fthe present instance, I have described my invention in connection with a two-speed steering arrangement more clearly shown and described in my copending application, Serial No. 669,907, filed May 15, 1946, but it will be understood that my inventionwill work with but one pump and one control valve for pump flow. The specific valve devices shown include what may be called a small valve, which alone isrendered effective during slow speed steering, .and a second or large valve, which is rendered effective for the purpose of producing rapid or high speed steering motion. Both valves are actuated by the steering wheel or other controlling device, and whether one or both valves become effective depends upon the amount of motion imparted to the steering wheel, as will be described in my copending application last named. The controlling valve devices also include an automatic valve, sensitive to or actuated by relative motion between tractor and trailer, or responsive to their relative positions, and which takes care of necessary reversal of a booster servomotor as the crank which it operates moves to one side or the other of a dead center, as will also appear more in detail hereinafter.

The controlling valve devices are shown conventionally in Figs. 11y to l5 inclusive, which represent different positions of the valves for producing different eiects. These views do not illustrate the actual passageways and ports in casing 40 but are conveniently understood diagrams. For convenience in description the three valves, together with the ports and passages which they control, will be described in advance of description of their manner of operation.

The valve devices include a small valve 48, a large valve 49, both operator operated, and an automatic valve 50, each in the form of an annularly grooved cylindrical piston valve slidable back and forth in an opening in the housing or body 5l o'f valve unit 40. The lands and grooves of each valve member cooperate with the surrounding annular lands and grooves in the valve body, the several body grooves communicating with channels or passages leading to and from various devices, as is customary in this type of valve, and as will appear more in detail hereinafter. Valves 49 and 50 are alike. Valve 48 is of similar form but of lesser diameter.

Valve 48 is provided with four V,annular grooves or channels marked, respectively, 48a, 48h, 48e. 48d, Fig. 11. Valve 49 likewise is provided with four annular grooves or channels marked, respectively, 49a, 49h, 49e and 49d. Valve 50 is provided with four similar grooves or channels marked 59a, 50h, 50c and 50d.

Valves 48 and 49 are connected by links 52 to arms 53 on a vertical shaft 54-having another arm 55 connected by a long link 56 to an arm 51 on a shaft 58 provided at its upper end with a manually operable operating device, Vsuch as the s steering wheel 59. This steering wheel, and the usual post in which its shaft is mounted, are supported upon a platform 6l mounted on the trailer and supporting the drlver's seat 6|, conventionally indicated in Fig. 7. The shaft 54, before referred to, is also provided with another arm 62, Fig. 4, connected by a clevis 63 to a rod 64 slidable in a bracket 65 mounted on the valve casing 5l and which supports four compression springs, two marked 66 and two marked 61, mounted 0n rods 63 carried by arms of the bracket 65. Rod 64 is provided with a depending arm or plate 64a lying between the inner ends of the rods 68, those rods which support springs 66 being shorter than those which support springs 61, as shown in Fig. 3.

The result is that, assuming the steering wheel in normal or neutral position, with the tractor and trailer in line with each other and traveling along a straight road, upon movement of the steering wheel in' either one direction or the other, both the small and large valves 48 and 49 are moved together in one direction or the other. Only one of these valves is necessary to effect the steering in accordance with the invention being claimed here, the other being used vfor two-speed steering as described in the abovementioned copending 'application Serial No. 669,907. During the initial or early stage or zone of motion of the steering wheel, one of the springs 61 is compressed until the head on the longer rod which carries it is pushed back far enough so that plate 64a engages the head of the shorter rod `68 beside it. Thereupon spring 66 begins to be compressed, and from that point on, throughout this second zone of motion, both springs are compressed. 'I'he initial motion, through the first zone, requiring less effort by the operator, renders only the small valve and its small capacity pump effective, for slow speed steering, while the additional motion, through the second zone, renders the large valve and its greater capacity pump effective, for high speed steering. When the operator encounters the additional resistance of a spring 66, he knows that both valves and both pumps are becoming effective for high speed steering. When the operator releases the steering wheel the springs 66, 61 return the valves and Wheel promptly to neutral position. kOf course, graduating effects may be secured by adjustment of the valves to various intermediate positions in either of said zones.

Fig. 7 illustrates the operating parts in neutral position, where the tractor and trailer are in line, traveling along a straight road. Piston 32 of primary servomotor 34 is in mid-position, from which it advances for steering to the right and is retracted for steering to the left, in both cases working at maximum eiiciency, with due respect for the sine law. The piston of booster motor 35 however is fully retracted, because that motor is on dead center with respect to the crank axis I2, as a consequence of which it is necessary to reverse the ow of fluid to the two chambers 35a, 35h of the booster motor as the crank which it operates moves back and forth across dead center.. The valve mechanism includes an automatic device t0 take care of this reversal, as will later appear.

The dual pump unit I6 of Fig. 6 is more clearly shown in Fig. 17. Shaft I 6a is provided with `a'suitable driving connection with motor l5.

asaaaae and Stil provide a pump of relatively large capacity, say, sixty-five gallons per minute. In a separate chamber of the housing, shaft i60. rotates gear 39| which meshes with gear 392 on shaft 3931 which in turn is rotatably mounted in the housing. Gears 39| and 392 provide a pump of relatively small capacity, say, ten gallons per minute.

Referring now to Fig. 6, which diagrammatically illustrates the complete hydraulic system, pump 38, which is of relatively large capacity, is connected on its suction side by conduit 69 with the tank or reservoir l1, and on two discharge sides, by conduit 10 and a, suitable passage in swivel joint 43, and conduit 1|, with the controlling valve unit 40. In a similar manner the pump 39, which is of the same type but of smaller capacity than pump 38, communicates on its suction side, by way of conduit 12 and another suitable passage in swivel unit 43, with a conduit 13, and on its discharge side, by way of conduit 14 and the swivel joint, with a conduit 15, conduits 13 and 15 being later referred to.

Referring also to Fig. ll, supply pipe 1| from the large pump communicates with a passage 1B in the valve body, having two branches 11, 18. The valve body is also provided with a large outlet passage 19 communicating by pipe 80 with controlling valve unit 49, which is connected to a return pipe 8| communicating, by way of a passage in swivel joint 43 with a drain pipe 82 leading to the reservoir I1. Passage 11 communicates by pipe 83 with the pressure limiting or release .valve 4| from which a return conduit 84 leads to the check valve 42 which communicates, on its opposite side, with the conduit 13 before referred to.

The supply pipe 15, coming from the small pump, communicates by pipe 85 with a passage 86 in the valve body, having three branches marked respectively 81, 88, 89, Fig. 1l, and by way of pipe 90 with relief valve 4|, where liquid flowing through the small pump system joins that flowing through the large pump system as shown in Fig. 6. Y

Primary servomotor 34 is connected to the controlling valve mechanism by two conduits, to wit, conduit 9| leading from chamber 34a to a passage 92 in the valve body, and conduit 93 leading to a passage 94 in the valve body. Similarly chamber 35a of the booster motor communicates by pipe 95 with a passage 96 in the valve body having two branches marked respectively 91, 98, while chamber 35h communicates by pipe 99 with a passage having two branches marked respectively |0I, |02.

Booster servomotor 35 is not essential and in some cases may be omitted, in which case, of course, conduits 95 and 99 and their connecting passages 96 and |00 with their branches, and automatic valve 50 will be omitted, and, for convenience, the control mechanism will be described first, as though that were the case.

In operation pumps 38 and 39 operate continuously, a supply of oil being delivered by each of them to the appropriate supply passages 16,'

86 in the controlling valve unit 40. Such oil as is required for actuation of a servomotor piston enters its active motor chamber, the oil from the inactive chamber flowing on to be returned to the pump or other reservoir, it being understood that relief valve 4| is loaded to maintain any desired pressure in the system.

Fig. 1l illustrates all parts in neutral or normal position, as when the vehicle is traveling along a straight road and the operator has per'- mitted the steering wheel to return to neutral position.

7lhe passage 86, supplied by the small pump. communicates by branches 81, 88 with channels 43a, 48o which are lapped or closed in the valve body. Branch 89, however, communicates by channel 48d with a branch |03a of passage |94 communicating byA pipe |05, Fig. 6, with the return conduit 13 for the small pump system. Passage 16, which supplies a larger quantity of oil from the large pump, communicates by its branch 11 with channel 49a which is lapped or closed and by its branch 18 and channel 49o with a branch' Illia of passage 19, which communicates with the conduit before referred to, for returning the oil from the large pump system to the reservoir, by way of valve 44, conduit 8|, etc., and with the relief valve 4| by way of conduit 83. Passages 92, 94 are lapped or closed. As a result, the primary servomotor 34 is inactive, its piston remaining stationary, and the pumps continue in operation, circulating oil against the pressure of the relief valve without effect upon the steering mechanism.

Let it be assumed that, at a time when the steering effect has been to the left, the operator desires either to straighten up or turn to the right. Valve 50, therefore, is in its extreme left position, Fig. 12, for reasons which will later appear. The operator turns the steering wheel to the right, or clockwise, Fig. '1, which simultaneously advances the small and large valves 48, 49 to the right in Fig. 1l to the positions shown in Fig. 12. For slow speed steering the steering wheel is moved only a short distance, as described in my copending application Serial No. 669,907, only sufficient to compress a spring 61, or until the plate 64a engages one of the rods 68 supporting a spring 66, but without compressing the latter spring.

So long as the operator holds the Wheel over in its new position, steering effort is applied to produce swinging motion of the tractor with reference to the trailer, or of the two with reference to each other, by causing flow of oil as follows:

The large pump is not effective. Branches 11 and 18 from its supply passage 16 are lapped or closed, so that its oil stream flows to the relief valve and thence back to the reservoir. The small pump however is effective, its oil supply ilowing from passage 86 by way of branch 81 and channel 48a to passage 92 and thence by way of conduit 9| to chamber 34a. Chamber 34h is in communication, by conduit 93, with passage 94, which is connected by channel 48h with a branch of passage |04, for returning the oil supply to the small pump.

The result is the advance of piston 32 in the cylinder 0f the primary motor, the rod of which turns crank 21 clockwise in Fig. '1, about the hitch axis |2, and the vehicle is steered to the right. The steering eect is cumulative, building up by further relative motion between tractor and trailer, until the parts can go no further, or until the operator relieves his pressure on the stetring wheel and said wheel and the other steering parts return to their neutral positions, under the influence of springs 61, as described.

If the road turns sharply to the right, as upon a short bend, requiring rapid or sudden relative steering motion between tractor and trailer, or should the curvature of the roadway, already gradual, suddenly increase, requiring like effect.

u then the operator swings the steering wheel turther to the right. sufficient to not only move the plate 64a against the heads of the short rods 68. but enough to actually compress the shorter springs 66. Such an eiort moves the valves 48. 49 to the positions shown in Fig. 13, the high speed steering position my copending application. Now thc motion of the piston in the servomotor 34 is produced by oil flow as follows:

From small pump passage 86 and its branch 81 by wa y of channel 48a to passage 92 and thence to chamber 34a. A larger supply of oil also flows from largo pump passage 16 and its branch 11 by way of channel 49a to the passage 92. From the chamber 34h on the opposite side of said piston oil flows by way of passage 94 and channel 49h to passage 06 and thence to discharge, and by channel 40h to passage |04 and thence to discharge.

Thus, by the rst increments of motion of the steering wheel to the right, the relative steering motion between tractor and trailer is produced at relatively low speed by the eiTect of the small pump alone, but when the steering wheel is advanced suiliciently so that both of the springs 66 and 61 are compressed, the same steering motion is etected more rapidly by a greater supply o*r oil coming from both the small and large pumps. This two-speed steering is claimed in my copending application, Serial No. 669,907. In both cases the discharge openings from the chamber on the inactive side of the piston are in proportion to the quantity of oil ow. In both cases the effect can be graduated by intervening positions of the steering wheel, which adjust valves 48 and 49 to various positions so that their annular grooves or channels open the valve ports and passages to greater or lesser degree.

Of course, as the vehicle straightens up, as upon a straight road, valve 50 returns to its neutral position, as shown in Fig. 14, due to motion of crank 21, as will later appear.

Steering motion in the opposite direction, to the left, while the vehicle is turning to the right, is accomplished by turning motion of the steering wheel in the counterclockwise direction, Fig. 7,-

with corresponding adjustment of valves 48 and 49 to the positions shown in Fig. 15, and with like effects, but eiective to produce pressure in chamber 34h, which becomes the active chamber instead of chamber 34a. Here valve 50 is in its right-hand position, because crank l 01 has moved beyond the neutral zone and is assumed to be at position |01b. The vehicle is travelling to the right.

When the steering system includes the second or booster motor 35, automatic valve 50 is required, with operating connections therefor as shown in the drawings. The purpose of booster motor 35 is to oiset the reduction in turning torque, around the steering axis I2, of the steering motor 34, the two motors 34, 35 being so disposed, relatively to each other and with reference to said axis, that in either direction of steering turn an increase or reduction in torque of the steering motor 34 is offset or equalized by corresponding reduction or increase in torque of the booster motor. That is true, of course, only when crank |01, later referred to, moves in one direction or the other an amount suflcient to actuate valve 50. Valve 50 not only serves to connect the chambers of the booster motor 35 to those of the motor 34, so that the two operate in parallel or with cumulative eiect, as it were,l

during both low speed and high speed steering, but also in a manner to reverse they two cham- 10 bers of the booster motor 35 as the crank operated thereby passes to one side or the other of the dead center. This requires special operating connections for valve 50.

As shown in Figs. 2 and 7, the crank arm 21; to which turning eiort is applied for producing steering motion, is provided with a crank pin |01, Fig. 7, to which is connected one end of a rod |08, Fig. 2, provided with a head |09 trav- 1 elingr back and forth within a short sleevelike insert ||0 in a long tube IH. provided at both ends with caps ||2. In opposite ends of said tube are located compression springs H3 each seated at one end against a cap 2 and at the opposite end against a washer |14, one of which surrounds rod |08. To the far end of the tube I|| is secured an extension rod ||5 loosely slidable in an opening ||6 in a bracket extension I1 of the body 5| of the valve unit 40, just above the automatic valve 50. An arm I8 welded to the cap ||2 extends downwardly and is pivotally connected by a pin H9 to the end of the valve 50. On the rod 5, one on either side of bracket H1, are compression springs |20.

As the crank 21 is turned to one side or the other from its neutral position, the crank pin |01, shown in full lines in Fig. '1 in its neutral position, moves to one or the other of the positions shown in dotted lines in said View at |01a or |01b. That motion of pin 01 causes longitudinal motion of rod |08. The position of the automatic valve 50, therefore, always depends upon the position of crank 21 and never upon a direct eiort of the operator. f

Fig. 2 shows the parts in neutral position, the head |09 lying midway between the two washers I4. The first increments of motion of the crank pin |01 fromits neutral position, cause the head |09 to slide idly within tubes |I0, until a;k washer H4 is encountered. During this zone of motion, a few degrees on either side of the dead center, the position of valve 50 is unaffected. It remains in neutral position, as shown in Fig. 11. But, as the crank 21 is moved further, the head 09 moves further, carrying with it the washer |I4, the tubes ||0 and HI, arm H8 and Valve 50, which is promptly` moved in one direction or the other, either to its extreme left-hand position shown in Fig. 13 corresponding to crank pin position |01a, or to its extreme right-hand position shown in Fig. 15 corresponding to crank pin position |01b. with compression of one or the other of springs |20. After the valve has been thus fully moved, further motion of crank |01 merely compresses one or the other of springs 4| I3, without further valve motion, those springs being provided merely for the purpose of securing lost motion of crank |01, when necessary, beyond the point where valve 50 has been fully shifted.

In neutral position of valve 50, when the crank of booster motor 35 is on dead center, as in Fig. 7, such neutral position being shown in Fig. 11, the vehicle is traveling directly forward in a straight line. The passages 96 and |00 are lapped or closed in the channels 50a, 50h, but are cross-connected at channels 50c, 50d by passage |06a, leading to the discharge passage 80, all communicating with the large pump supply passage, according. to the position of valve 49.

position marked l'la, Fig. '1, the valve 50 is in its left-hand position shown in Fig. 12. In the position shown in Fig. 12 the vehicle is actually turning to the left, because crank arm 21 has been moved counterclockwise in Fig. 7, but the steering effect of valves 48, 48 is to the right. Passage 92, which communicates with chamber 34a of the primary motor, is connected by means of channel `Elib with the passage IUI communieating with chamber 35h of the booster motor. At the same time, channel 94, connected to chamber 34h, communicates by channel 50c with chamber 35a, by way of channel 48h and passage |04, the chambers 3417 and 35a are connected to exhaust. Thus, the propulsive effort of the piston in cylinder 34 is in one direction, say outward, while the propulsive eort of the piston in cylinder 35 is in the opposite direction, say inward.

When the crank pin |01 reaches a position on the other side of the dead center, say as indicated at I81b, Fig. 7, valve 5B is in its extreme opposite direction, or at the right, as shown in Fig. 15, and the vehicle is turning to the right, but the steering effect is now being initiated to the left by virtue of the setting of valves 48 and 49. And, it will be apparent, chamber 34a now communicates with chamber 35a both connected to exhaust, and chamber 34h with chamber 35h both connected to the pressure source. Thus, in this case, the propulsive efforts in the two cylinders are now in the same direction.

The result of all of the foregoing is that when both primary and booster steering motors are employed, with operating mechanism as illustrated, the operator steers the tractor and trailer by turning the steering wheel in one direction or the other. Within a zone including a few degrees in either direction. from neutral, the booster is out of commission, as it were, its piston being moved idly by the operative eect of the crank pin |01 or crank 21. In this zone steering effect is produced by the primary motor alone, with the supply of oil coming either from the small pump alone, during low speed steering, or from both pumps, if the steering wheel has been pushed far over and high speed steering is required. As the steering eilect, i. e., the angular relation between tractor and trailer, increases, valve 50 is automatically operated, by motion of crank |01, to connect the chambers of the booster cylinder into the fluid pressure system, and this always is with due regard for whether the crank operated by the booster cylinder is on one side or the other of its dead center.

It, of course, will be understood that in this steering mechanism, steering is not accomplished by turning the steering wheel in one direction or vthe other, through an angle, the magnitude of which determines the total amount of steering turn, and then leaving the wheel there, leaving it to the steering parts to produce the steering eiect. The steering here is accomplished by one or more impulses, the number and extent of which are selected to produce the desired eiect. In other words, assuming slow speed of travel of the vehicle, if a slow gradual turn in the road requires that kind of steering, the operator turns the wheel over only a few degrees, holds it there for possibly only a second or less, and immediately returns the wheel, or lets it return, to neutral position, repeating the operation if the steering swing is not sufficient. Likewise, if a short extensive turn, such as a right angle bend in the road, requires that kind of Steering, the

. l2 operator swings the wheel in the proper direction through a wide angle, so asto bring high speed steering into operation, promptly returning the wheel, or permitting it to return, to neutral position, and repeating the impulse if suicient effect is not secured. In either case, when the steering turn progresses to an amount which produces motion of valve 50, the booster cylinder automatically comes into operation. Thus, the operator has all parts of the mechanism within his control and by manipulations of the steering wheel, either short or long, and held long enough or repeated frequently enough, produces any kind of steering effect he desires.

Of course the primary cylinder motor 34 is most efficient when crank pin 28 is in the position shown in Fig. 7, and its efficiency decreases the further said crank departs from that position. But, as it departs, the control valve 58 throws the booster cylinder into operation, with an effect which increases or becomes more eiliclent as the effect of the primary cylinder decreases. Thus, substantially uniform propulsiva eiort is provided through the entire range of relative Steering motion.

It should also be noted that at any time when the booster servomotor is in operation, by reason of automatic adjustment of valve 58 to either of its two operating positions shown in Figs. l2 and 15 respectively (crank at Ill'la or 1811i) the valve 48, or valves 48 and 49 together, serves as manually operated control means to which the booster servomotor is subject. In other words. in both of these positions, iluid pressure never can reach and become effective in the boosterservomotor unless the operator manually has adjusted valves 48, 49 to either slow speed or high speed steering position, either to the right or to the left. Booster motor 35 never can become effective alone.

Other advantages of the invention will be apparent to those skilled in the art.

What I claim is:

l. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch axis, two fluid pressure servomotors mounted upon one of said members, a crank arm carried by the other member and operatively connected to each servomotor, one motor being effective at an angle with respect to the crank arm and the other at dead center with respect thereto when the tractor and trailer are in line, means for supplying fluid pressure to both servomotors, and means sensitive to the angular relation betweentractor and trailer for controlling the supply to said other motor as the crank moves away from its dead center relation with said second motor.

2. Apparatus of the character described, comprising tractor and trailer members pivotally connected together -on a vertical hitch axis, two fluid pressure servomotors mounted upon one of said members, a crank arm carried by the other member and operatively connected to each servomotor, one motor operating at an angle with respect to the crank arm and the other at dead center with respect thereto when the tractor and trailer are in line, a source of iluid pressure supply connecting said motors, manually operable means for controlling connection of said source to the first servomotor, and means sensitive to the angular relation between tractor and trailer for controlling connection of said source to the second servomotor.

3. Apparatus of the character described, com-l prising tractor and trailer members pivotally connected together on a vertical hitchv axis, one of said members being provided with crank means, two servomotors provided with piston rods connected to said crank means, and a source o! fluid pressure supply for said servomotors, said piston rods being eiective upon said crank means at approximately right angles to each other with the crank pin lying in a region between said motors and the crank center, whereby the emciency of one servomotor increases as that of the other diminishes.

4. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch axis, and two ilud pressure servomotors nounted cn one member, said motors being of piston and cylinder form and having their piston rods at approximately right angles to each other when said trac- 'tor and trailer members are in line and both operatively connected crank-wise to the other member, whereby one motor supplements the other motor at the zone of the other motor's lowest efliciency.

5. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch axis, two iluid pressure motors mounted upon one of said members, a crank arm carried by the other member and operatively connected to each servomotor, means for supplying iiuid pressure to both servomotors, and means sensitive to the angular relation between tractor and trailer for controlling the supply to one only of said motors.

6. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch axis, two fluid pressure motors mounted upon one of said members, a crank arm carried by the other member and operatively connected to each servomotor, means for supplying iluid pressure to both servomotors, means sensitive to the angular relation between tractor and trailer for controlling the supply to one of said motors, and operator operated means for controlling the supply to the other servomotor.

7. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch axis, one of said members being provided with a crank spaced from said axis, a fluid pressure motor mounted upon the other member and eiiective upon said crank upon either side of dead center relation with respect to the crank axis, a source oi' uid pressure supply therefor, controlling means for said supply arranged to render said motor ineffective when said crank lies in a neu-r tral zone near dead center and eilective when said crank lies beyond either side of said zone, and separate power means effective upon said one member to turn the same about said axis when said crank lies in the neutral zone.

8. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch axis, power means mounted upon one member and operatively connected to the other member for producing relative steering swing between them from extreme right to extreme left on either side of their intermediate straight line relation in which the power means is on dead center with respect to the member which it operates, an operator operated controller therefor, and a second power rmeans effective upon said members to supplement the eiort oi.' the ilrst Apower means when 14 said members are near to. said straight line relation and said ilrst power means is near dead center.

9. Apparatus of the character described, comprising a train including tractor and trailer members pivotally connected together on a vertical hitch axis, two fluid pressure servomotors mounted upon one of said members, each including a cylinder, pistonA and rod with the rod pivotally connected to the other member at a crank point eccentric to the said axis, said two servomotors being severally so located on the member on which they are mounted that when the tractor and trailer are in neutral position and thus travel in a straight path one motor piston rod is on dead center and the second is at an angle with relation to said axis and crank point, so that both motors cannot be on dead center at the same time, and a source of uid pressure for said motors.

10. Apparatus of the character described in claim 9, including manually operatable means for controlling the flow of uid from said source to and from both motors, and means sensitive to the angular relation between the tractor and trailer for reversing the direction of ilow oi' iluid to and from said one motor in accordance'with the direction of steering turn of the train.

11. Apparatus of the character described in claim 9, in which the motor pistons and cylinders are further so located that in neutral position the piston of said one motor lies at the beginning of its stroke and that of the second motor at the middle point of its stroke, and including manually operatable means for controlling the iiow of fluid to and from both motors.

12. Apparatus of the character described in claim 9, including manually operatable means for controlling the flow of fluid from said source to and from both motors, and means sensitive to the angular relation between the tractor and trailer for reversing the direction of iiow of iluid to and from said one motor in accordance with the direction of steering turn of the train, the motor pistons and cylinders being further so located that in neutral position the piston of said one motor lies at the beginning of its stroke and that of the second motor at the middle oi' its stroke.

13. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch aids, a double acting servomotor vmounted upon one oi' said members and effective upon the other, a crank on said other member upon which said servomotor is effective, a booster motor connected with said crank, said crank and booster motor lying at dead center relation with respect to said booster motor when the tractor and trailer are in line, a source of fluid pressure supply connectedto said servomotor, means sensitive to the angular position of said crank for varying said connection according to that side of dead center upon which the servomotor is effectiveand manually controlled means cooperating with said servomotor for shifting said crank back and forth across dead center.

14. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch axis, one of said members being provided with a crank spaced from said axis, a fluid pressure primary motor mounted upon the other member and effective upon said crank and operating back and forth across dead center relation with respect assumes to the crank axis, a booster motor connected with said crank. and controlling means for said supply arranged to control said primary motor and also to render said booster motor ineffective when said crank lies in a neutral zone near dead center of said booster motor relative to the .crank axis and to render said booster motor eiective when said crank lies beyond either side of said zone.

15. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch axis, a first power means mounted upon one member and operatively connected to the other member for producing relative steering swing between them from extreme right to extreme left on either side of a neutral straight-line position of the members, an operator operated controller therefor, a second power means eiective upon said members to supplement the eiort of the rst power means when said rst power means is near dead center, and means operated by relative motion between said members for controlling said second power means.

16. Apparatus of the character described, comprising tractor and trailer members pivotally connected together on a vertical hitch axis, Aa first power means mounted upon one member and operatively connected to the other member for producing relative steering swing between 16 them from extreme right to extreme left on either side of a neutral straight-line position of the members, an operator operated controller therevfor, a second power means eiectiveV upon said members to supplement the effort of the first power means when said first power means is near dead center, said controller being movable in either direction from a mid position according to the desired direction of swing, and yielding means biasing said controller toward mid position.

GEORGE E. ARMINGTON.`

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

